Sink



FIG. 1 is a perspective view taken from the top, front and left end of "a sink" showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof, the rear elevational view being a mirror image of the front shown;

FIG. 4 is a left end elevational view thereof; and

FIG. 5 is a right end elevational view thereof. 

The ornamental design for a sink, as shown and described. 